Under present wire manufacturing procedures it has been more economical to scrap large quantities of PVC coated wire when insulation faults are detected than to save the wire, locate the points of fault and repair the defective regions. If an automatic apparatus which could detect, locate and repair and preferably retest faults in such wire were available, it would become economical to make use of wire which would normally be scrapped.
Fault detectors for PVC insulated wire are known and are presently used in the manufacture of PVC wire. One such fault detector is known as a bead-chain fault detector. This detector is a high voltage spark detector wherein the wire to be tested is drawn through a bed containing a multiplicity of small metal beads hanging on metal chains to form a bead curtain in a metal enclosure. The beads and enclosure are held at a given DC potential, typically several thousand volts, while the wire to be tested is held at ground potential. If wire having an insulation fault passes through the detector a current path is formed between the beads and the wire conductor at the fault. Control circuitry associated with the detector detects the current flow, triggering the detector to record the presence of a fault. In past practice, this detector has only been used to indicate the presence or absence of a fault. At the high line speed at which wire is processed, typically about 3,000 ft. per minute, the time required to slow down and/or stop the wire may allow many feet of additional wire to pass through the detector. The stopping time may vary considerably due to the difference in inertia between full and empty wire take-up reels. Consequently the substantially exact location of the fault was not known. We have developed a machine which, after detecting the presence of a fault based upon the prior art method, is then capable of automatically locating, repairing and preferably retesting the fault such that an entire reel of wire can be used without any waste.